Which forms of luggage protection don't TSA and airline ticketing agents find objectionable? [closed]

I am sick and tired of airlines doing damage to my suitcases, telling me wheels, handles, and zippers are "only cosmetic" and then, adding insult to injury, making me sign a waiver before they'll accept the same suitcase that they damaged on a later trip.

The suitcases are not cheap, but the cost of shipping them back repeatedly for warranty claims is not worth it.

So what are some preventative measures I can take?

Sometimes I ask for them to be tagged as fragile. But then I have to sign the waiver. Seems to defeat the point. Or maybe not, since they rarely take responsibility for damage anyway.

Sometimes I ask for my suitcase to be wrapped in one of those large plastic bags. But I often fly Southwest, which either doesn't provide them, or doesn't like to provide them.

• If I use my own contractors trash bag but it is opaque black instead of clear, will the agent or handlers or TSA throw a fit?

• Or if I reuse a bag from another airline, would that encourage the airline to lose my suitcase?

The saran wrap service isn't that common at U.S. airports. While I could wrap it myself, TSA will just cut it off to search the bag.

Sometimes I use a cardboard box as disposable luggage. Still have to sign the waiver for the contents, because according to the agent they are "not properly packed." This works as a second checked piece if my first checked piece has wheels and is sturdy enough to use as a dolly.

• If I put my suitcase in a cardboard box, or constructed a cardboard jacket to wrap around the suitcase, would I still have to sign the waiver?

• Could I depend on TSA to tape it back up?